Guidewires are used in most catheter-based procedures. The distal end of a guidewire typically has an angled tip, which can be oriented to help steer the guidewire through curves and junctions of the vasculature or vessels of a patient. The orientation of the angled tip is achieved by torqueing the guidewire so that it rotates about its axis. However, since the guidewire has a small diameter and typically a smooth surface, it is difficult to torque with an operator's fingers. Torqueing requires the aid of a larger diameter torque device, which is attached to the guidewire.
One common type of prior art torque device is referred to as a pin-vise device. A pin-vice device has a structure somewhat similar to a miniature drill chuck with a cylindrical handle. The device has multiple parts. A cap is screwed down over a collet, which in turn grips a guidewire running through the collet. The device is typically backloaded over the guidewire from the proximal end. The cap is rotated with respect to the handle, which tightens the collet and grips the wire. At that point, the device can aid in the manipulation of the guidewire, either rotational or longitudinal. Among the disadvantages of the pin-vise-type torque device is that it has multiple parts and requires two hands to operate. In addition, the device must be backloaded over the proximal end of guidewire.
An example of a prior art pin-vice type torque device is shown in U.S. Pat. No. 5,851,189, to Forber. The '189 patent teaches a torque device for attaching to and selectively gripping and releasing a catheter guidewire to permit rotational and longitudinal manipulation of the guidewire to steer the guidewire through a vessel. A spindle is threadably engaged in a cap, and a bore through the spindle aligns with a bore through the cap to accept the guidewire. The end of the spindle inside the cap has a pair of fingers straddling the guidewire. As the cap and spindle are rotated with respect to each other, the threaded engagement of the spindle and cap forces the end of the fingers to advance along a tapering bore in the cap, which causes the fingers to close and grip the guidewire. Reversing the direction of rotation releases the grip on the guidewire.
Another prior art guidewire torque device is shown in U.S. Pat. No. 5,392,778, to Horzewski. The '778 patent teaches a torque device that is backloaded over the end of a guidewire and which a user can then operate with a single hand to grip the guidewire and to release the guidewire. The device is formed from a pair of tubular members, one of which terminates at one end in a multitude of prongs and the other fitting over the prongs in a manner permitting it to slide relative to the prongs and to the first tubular member in the axial direction. The tubular members are hollow to permit passage of the guidewire, and the tips of the prongs encircle the central axis of the device, likewise to permit passage of the guidewire. The prongs are shaped such that their tips are far enough apart to permit unimpeded axial movement of the device over the guidewire, but the prongs are of a resilient construction, permitting them to be bent or compressed toward each other to grip the guidewire on all sides. A circular protrusion or ring on the interior of the second tubular member extending inward contacts the sloping outer surfaces of the prongs such that when the second tubular member is slid over the prongs with the ring moving toward the prong tips, the ring compresses the prongs, causing the tips to close over and grip the guidewire. The two tubular members are readily moved relative to each other with a single hand. Thus, once the device is backloaded over the end of the guidewire, a single hand may be used to make the device both grip the guidewire and release the guidewire.
Another prior art guidewire torque device is shown in U.S. Pat. No. 5,312,338. The '338 patent teaches a guidewire torque device formed as a gripping-knob rotational tool. The device includes a slot for engaging the guidewire from the side. The device is comprised of a tubular housing that is formed from two cylindrical members that are adapted to fit together in a telescoping arrangement. The two members are provided with a passageway that runs through the length of each member. A slot also runs the length of each member and extends from an outer surface of each member to the passage way running therethrough. In operation, the guidewire is placed into the longitudinal slot and the two cylindrical members can then be rotated relative to each other to a first position which locks the guidewire within the device, but without securing the guidewire to the device. In this position, the device is in a first gripping mode. The cylindrical members can then be rotated to a second position which causes an elastomeric member to twist around the guidewire, but without bending the guidewire.
One of the disadvantages of prior art guidewire torque devices such as those shown above is that they require multiple moving parts which are subject to breakage, and which are relatively costly to manufacture. In addition, devices such as those taught in the '189 and '778 patents must generally be backloaded over the proximal end of the guidewires. Furthermore, the devices of the '338 and '189 patents generally require two hands to operate.